A Study On Heterogeneities Of Chang6 And Chang8 Reservoirs Of Yanchang Formation At Shangliyuan Area In Ordos Basin

The reservoir of the chang6 and chang8 of Yanchang Formation, Upper Triassic at Shangliyuan area in Ordos basin is part of low- porosity and permeability. In this thesis, we start the study base on the reservoir character of strong heterogeneity, diversiform diagenesises, complex and inhomogeneous distribution of the porosity structure. We analyse the heterogeneity character and the influencing factors in studying area, then expatiate the influence on storage body capability of reservoir, at last classified systematically and evaluated integrately to the reservoir.Base on the drilling and logging data, making using of many technical means such as observation to rocks, image analysis of cast thin section, scanning electron microscope, high-pressure mercury injection, etc. Many theories and technological methods related to sedimentology, lithofacies and paleogeography, petroleum geology, borehole geophysics are used in the paper. We make a systemic study to the reservoir heterogeneity of Shangliyuan area in Ordos basin.Achievements of the paper are as follows:1. The maturation degree of oddment grain and sandstone component is low, filling of clay and strong compaction and cementation which result in complex porosity structure and strong microcosmic heterogeneity.2. Sedimentation of the reservoir control the special distribution of sandbody and the rock property of reservoir. The diagenesises effect the reservoir parameter special distribution and the grade of reservoir heterogeneity in plane and portrait.3. The strong heterogeneity mainly distribute to the sandbody of underwater distributary channel, also the heterogeneity of thick sandbody that distributary channel superposed is strongest. The heterogeneity of bayou bar and the channel margin is of a sort. In the mass, the reservoir heterogeneity of chang8 is stronger than chang6.4. Compared the storage body capability of chang6 reservoir with chang8, we had a conclusion: the best capability of storage oil are chang8₂, chang8₁ and chang6₃, the total area of the most advantageous region and advantageous region are big, the productivity of chang8 is bigger than chang6, the capability of storage oil of chang6₁ is of a sort.